Method of effecting a temporary securement



May 20, 1969 T. J. SARGENT 3,444,573

METHOD OF EFFECTING A TEMPORARY SECUREMENT Filed July 18, 1967 INVENTOR.xgw I71omas J. Sci/yen) United States Patent US. Cl. 12-142 4 ClaimsABSTRACT OF THE DISCLOSURE There is disclosed herein the temporaryattachment of a porous insole to the impervious bottom of a last bymeans of a cement plug that has a surface adhesion with the last bottomthat is released with the passage of time and a mechanical interlockwith the insole.

This invention is concerned with the temporary securement of therelatively porous surface of a first member and the relativelyimpervious surface of a second member by means of a plug of cementinterposed between the members in such a manner that when the membersare parted the plug is detached from the impervious surface and remainsadhered to the porous surface.

In the illustrative embodiment of the invention, the first member takesthe form of a relatively porous insole and the second member takes theform of a last having a relatively impervious surface on its bottom. Thetemporary securement is effected so that shoe manufacturing operationsmay be performed on the insole-last assembly, after which the insole isseparated from the last.

In the drawings:

FIGURE 1 is a plan view of the insole and last prior to securement;

FIGURE 2 is a side elevation showing the pressing of the insole to thelast bottom to effect securement;

FIGURE 3 is a cross-section to an enlarged scale of the insole securedto the last bottom by a plug of cement; and

FIGURE 4 is a view of the last-insole assembly with an upper lastedthereto.

The method of this invention is disclosed as being preformed by themachine shown in pending application Ser. No. 610,097 filed Jan. 18,1967. The machine is used to temporarily attach an insole to the bottomof a last 12 by means of plugs of cement 14, 16 and 18. The plug 14 isapplied to the last bottom and the plugs 16 and 18 are applied to theinsole. The insole 10 is then pressed against the bottom of the last 12,while the last is supported bottom-up, by pressing members 20 and 22 tothereby attach the insole to the last bottom. Conventional shoemanufacturing operations are then performed on the assembled last andinsole such as lasting an upper thereto, bottom roughing, outsoleattaching, etc. After this, the finished shoe is removed from the last.

The cement utilized is of the delayed tack type and is applied in moltencondition to the last bottom and insole. The insole is made of arelatively porous fibrous material such as paperboard or leatherboardand the last bottom is made of a relatively hard impervious materialsuch as wood, plastic or steel.

The delayed tack cement, which is thermoplastic, is composed of anintimate mixture of a resin and a plasticizer. After application to theinsole and the last bottom, the cement cools rapidly to roomtemperature. However, the cement remains in a tacky and fluent conditionfor a period of time after application to the insole and the lastbottom, after which the plasticizer crystallizes and the cement losesits tackiness and fluentness.

Referring to FIGURE 3, pursuant to the pressing of the insole 10 againstthe bottom of the last 12 by the pressing members 20 and 22, the cementplugs 14, 16, 18 adhere to the impervious last bottom by surfaceadhesion without penetrating the last to any substantial extent. Due tothe porous nature of the insole, the pressure created by the pressingmembers 20 and 22 cause the fluent cement plugs 14, 16, 18 to penetratethe interstices of the insole to some extent to thereby adhere to theinsole by a mechanical interlock.

The pressing members 20, 22 are released from the insole after enoughtime has elapsed for the cement plugs to effect an adherence of theinsole to the last bottom. After this the shoe manufacturing operationsreferred to above are performed on the last-insole assembly and the shoeis removed from the last in the conventional manner. Before theplasticizer has crystallized sufficiently to terminate the surfaceadhesion between the cement plugs and the last bottom, the insole hasbeen anchored to the last by the lasting operation which causes thestretching of the margin 24 of an upper 26, that is mounted on the last,about the last 12 and the attachment of the upper margin, as by cement,to the insole 10 (see FIG. 4). The shoe is removed from the last aftersufficient time has elapsed for the plasticizer to crystallizesufliciently so as to terminate the surface adhesion between the cementplugs and the last bottom.

From the foregoing it can be seen that the insole is attached to thelast by a permanent mechanical interlock between the cement plugs andthe insole and a temporary surface adhesion between the cement plugs andthe last bottom. The surface adhesion is retained until after the insolehas been anchored to the last bottom by means other than the cementplugs. When the shoe is removed from the last, the cement plugs remainadhered to the insole due to the mechanical interlock and separates fromthe last bottom due to the termination of the surface adhesion. Withthis arrangement the last bottom is free of cement so that the last canbe used again without scraping any cement particles from its bottom. Theplugs of cement adhered to the insole are so thin that they do notcreate any discomfort to the wearer of the finished shoe.

There are many commercially available delayed tack cements that.aresuitable for use in the above described method. Each of those used inthe illustrative embodiment of the invention comprises a solid,crystalline plasticizer that has been mixed with a resin after the resinhas been heated from its normally solid condition into a moltencondition to thereby form a molten resin-plasticizer combination. Aftermixture, the cement is allowed to cool to a solid condition and isstored until it is to be applied to the insole and last bottom at whichtime it is reheated to a molten condition.

The following are among the cements that can be used. The indicatedpercentages are by weight. Versamid 940 and Versalon 1160 are suppliedby General Mills Chemical Division, Kanakee, 111., Elvax 40 is suppliedby E. I. du Pont de Nemours and Company of Wilmington, Del., Santicizer9 is supplied by Monsanto Chemical Company of St. Louis, Mo., andPentaerythritol Tetrabenzoate is supplied by Velsicol ChemicalCorporation of Chattanooga, Tenn.

1. A method of etfecting a temporary securement between a relativelyporous surface of a first member and a relatively impervious surface ofa second member comprising: applying at least one plug of cement to atleast one of said surfaces, the cement being so constituted as to beinitially tacky and to lose its tackiness after the lapse of a timeperiod; pressing the surfaces against each other within said time periodso as to cause the cement plug to penetrate said porous surface andadhere thereto by a mechanical interlock and to cause the cement plug toadhere to said impervious surface by a surface adhesion so that anoperation may be performed on at least one of said members; and removingthe first member from the second member after the lapse of said timeperiod whereby the plug is separated from said impervious surface due tothe termination of the surface adhesion and remains adhered to saidporous surface due to the mechanical interlock.

2. The method as defined in claim 1 further comprising: effecting anoperation on at least one of said members within said time period whichcauses the membersto be anchored to each other by means other than thecement plug.

3. A method of effecting a temporary securement between .a relativelyporous surface of an insole and a relatively impervious surface of thebottom of a last comprising: applying at least one plugs of cement to atleast one of said surfaces, the cement being so constituted as to beinitially tacky and to lose its tackiness after the lapse of a timeperiod; pressing the surfaces against each other within said time periodso as to cause the cement plug to penetrate said porous surface andadhered thereto by a mechanical interlock and to cause the cement plugto adhere to said impervious surface by a surface adhesion; effectingshoe making operations on the last-insole assembly including anoperation, effected within said time period, which causes the insole tobe anchored to the last bottom by means other than the cement plug; andremoving the insole from the last after the lapse of said time periodwhereby the plug is separated from the impervious surface of the lastbottom due to the termination of the surface adhesion and remainsadhered to the porous surface of the insole due to the mechanicalinterlock.

4. The method as defined in claim 3 wherein the said operation effectedwithin said time period consists of the attachment to the insole of themargin of an upper that is mounted on the last.

References Cited UNITED STATES PATENTS 2,701,887 2/1955 Nolan 12l422,893,026 7/1959 Sillars et a1 12l42 2,984,847 5/1961 Maesel' 12-1PATRICK D. LAWSON, Primary Examiner.

